In marketing of fresh produce, namely fruits, vegetables and fowl eggs, several weeks may pass from harvest of the agricultural produce or gathering of the eggs, to the sale and use of the fresh produce. During this time, aerobic respiration continues through the semi-porous skins of the fruits, vegetables, and eggs. In fruits and vegetables, senescence is induced in this period by continued release of the plant hormones ethylene and auxin, which results in breakdown of sugars and evaporation of water from within the fruit. This aging in fruits and vegetables, is unwanted, since it results in obvious changes in the outer appearance, in the texture and in the taste of the produce. In fowl eggs as well, dehydration and aerobic respiration occur through the eggshell, and spoilage of the egg occurs over time due to entry of microorganisms through minute pores in the shell. Prior art attempts at delaying the aging process in fresh produce involve coating the produce with a film to decrease the rate of respiration. The coatings in use are semi-porous, since a totally impermeable coating leads to anaerobic respiration within the produce, which results in fermentation and spoilage. Often a wax is used in combination with a fungicide; the wax also provides the fruit with a shiny, desirable appearance. Polyethylene coatings have been used in the past. Currently, a widely used treating reagent is sodium orthophenylphenate (SOPP), which ionizes in solution to orthophenylphenol (OPP). Fruits are usually coated by soaking them in soaking tanks containing the treating reagents, or by applying the reagents in the form of a foam. U.S. Pat. No. 4,990,351 (Sunkist Growers, Inc.), relates to a method of application of SOPP to fruit. U.S. Pat. No. 5,101,763 discloses an automated apparatus for coating fruit with a first mixture of wax and fungicide, and a second coating of wax alone. U.S. Pat. No. 4,946,694 relates to a coating applied in a two-step process, useful to coat fruits that have sugary deposits on their skins (“sticky fruit”) such as dried fruits, dates and figs. First a mixture which includes a vegetable wax, vegetable oil and a wetting agent, is applied to the sticky fruit, then a second mixture which contains a protein is applied.
Organically grown agricultural produce is sought after by those who consider use of chemical treatment of fruits and vegetables to be a health hazard. Not only are chemical fertilizers unacceptable in the organic produce market, post-harvest treatments are equally unacceptable, such as application of chemical coatings on the produce. The need exists for a coating composition for protection of agricultural produce, deemed acceptable to the organic produce market. It is the object of the present invention to provide a composition for the coating of fruits and vegetables, which provides an answer to the demand for minimal chemical treatment of agricultural produce, yet protects and lengthens the shelf-life of the fresh produce. The composition of the present invention may be applied to organically-grown fruits and vegetables, as well as to the wider market which supplies the public with fruits and vegetables grown using chemical fertilizers. The present invention may be applied as well to fowl eggs of any source.
Certain natural waxes have been noted to be useful for protection of fruits and vegetables, when these waxes are applied as an external coating on the skin of the produce. Beeswax, candelilla wax, and carnauba wax have been used for this purpose. These natural waxes are highly concentrated and thus, cannot be applied without being diluted, since application of the concentrated form would result in a totally impermeable coating which would induce fermentation in the produce. These highly hydrophobic waxes need thus be formulated in a composition that can be applied evenly on all areas on the skin of the produce. U.S. Pat. No. 3,997,674 discloses a formulation essentially containing a natural wax, or a vegetable or mineral oil, and a high molecular weight polymer. Hagenmaier & Baker describe application of emulsions containing various combinations of natural waxes to Valencia oranges (J. Agric. & Food Chem. 45 (2), 349-352, 1997). Various coatings based on natural waxes have been described for a wide variety of fruits (Edible Coatings and Films to Improve Food Quality, Krochta, Baldwin & Nisperos Editors, Technomic Publ., N.Y., 1994, p. 37-50). None of the above-mentioned coatings would be acceptable to the organic produce market, for though they are based on natural waxes, they contain unacceptable synthetic additives that act as emulsifiers, plasticizers, anti-foaming agents, surfactants and preservatives (ibid.). It is the object of the present invention to provide a coating composition for protection of fruit, which does not contain synthetic additives unacceptable for the organic produce market.
These and other objects of the present invention will become more apparent from the detailed description of the preferred embodiments, that follows.